Automotive headlight system

ABSTRACT

An automobile headlight system comprises two elliptical reflectors each with a tungsten halogen lamp filament at or near one focus. From each reflector a light beam is projected through a light gate at the other focus and thence through a lens which cooperates with the elliptical reflector to throw a narrow light beam nearly parallel to the optical axis of the reflector and lens. The light gate before one lamp has a horizontally elongate aperture transmitting more light to the right beyond the lens. The light gate before the other lamp has generally vertically symmetrical aperture and transmits light higher above the horizontal than the first-mentioned light gate. The lamps are electrically connected to a power supply with a switching system such that they can be operated in three different modes: the first lamp at low voltage producing a low beam; the first lamp at higher voltage producing a low but brighter beam; and both lamps together producing a composite beam having high and low components.

United States Patent [72] Inventor Sandford C. Peek Ipswich, Mass. 211 App]. No. 19,882 [22] Filed Mar. 16, 1970 [45] Patented Nov. 2, 1971 [73] Assignee Sylvania Electric Products Inc.

[54] AUTOMOTIVE HEADLIGHT SYSTEM 4 Claims, 6 Drawing Figs.

[52] US. Cl 313/117, 315/82, 315/83 [51] Int. Cl. B60q l/l4, B60q H16 [50] Field of Search 315/76-80, 81-84;240/7.l,8.l,46.0l;313ll17,115

[56] References Cited UNITED STATES PATENTS 2,880,347 3/1959 Flaws, Jr. et al. 313/115 3,062,951 1 H1962 Falge 240/4601 X 3,136,914 6/1964 Jayneetal 313/117 Primary Examiner- Eli Lieberman Assistant Examiner-Marvin Nussbaum Attorneys.lames l-I. Grover and Norman J. O'Malley ABSTRACT: An automobile headlight system comprises two elliptical reflectors each with a tungsten halogen lamp filament at or near one focus. From each reflector a light beam is projected through a light gate at the other focus and thence through a lens which cooperates with the elliptical reflector to throw a narrow light beam nearly parallel to the optical axis of the reflector and lens. The light gate before one lamp has a horizontally elongate aperture transmitting more light to the right beyond the lens. The light gate before the other lamp has generally vertically symmetrical aperture and transmits light higher above the horizontal than the first-mentioned light gate. The lamps are electrically connected to a power supply with a switching system such that they can be operated in three different modes: the first lamp at low voltage producing a low beam; the first lamp at higher voltage producing a low but brighter beam; and both lamps together producing a composite beam having high and low components.

1; z; gx I RFSSWAY PATENTEDNUV 2 ml sum 1 [1F 2 AUTOMOTIVE HEADLIGHT SYSTEM All night driversare aware of the need for headlights which will shine in directions useful to the driver but with limited glare in directions towardother drivers. Federally adopted specifications for headlightbeams provide standards intended to meet the compromise between adequate, road illumination and the evidence of glare, and these standards must be met by any headlight system. However, previous systems have either met therequirement for adequate road illumination but exceeded the maximum allowable illumination without glare, or

have avoided glare at the expense of road illumination.

The object of the present invention is to provide a headlight system which meets or exceeds the minimum specifications for road illumination and yet which reduces glare well below the prescribed limits. I 7

According to this invention a vehicle headlight system comprises a first lamp, a second lamp closely adjacent the first, op-

tical means for projecting light from respective lamps on substantially paralleloptical axes, said optical means including a first mask in front of the first lamp having a horizontally elongate aperture with greater transmission to the right of the axis of the first lamp, and a second mask in front of the second lamp having a generally vertically symmetrical aperture transmitting substantially higher above its optical axis than the first aperture, and said lamps being adapted to be switched so as to operate in at least two different modes including operation of the first lamp alone and operation of the first and second lamps simultaneously,thereby to produce a low light distribution pattern substantially below a horizontal plane through said axes, or a second light distribution pattern which is a composite of light from both lamps.

For the purpose of'illustration a typical embodiment of the invention is shown in the accompanying drawing in which FIG. 1 is a vertical section of a single headlamp assembly with a light gate;

FIG. 2 is a section on line 2-2 of FIG. 1;

FIG. 3 Ba section like FIG. 2 showing a different light gate;

FIG. 4 is a schematic diagram of a headlight system with switched lamps producing three beam patterns according to the invention;

FIG. 5 shows two conventional beam patterns; and

FIG. 6 is a modification of the switched lamp arrangement of FIG. 4.

The headlamp assembly 1 of FIG. 1 comprises a canister 2 housing a lamp 3 with a coiled filament 4a located at or near one focus of an ellipsoidal reflector 6. At or near the other focus is an aperture disk or light gate 7a having an aperture 8a through which light from the reflector passes to a lens 9 and is projected therefrom through a conventional lenticular lens in a beam generally parallel to the axis A of the reflector 6 and lens 9. The light gate is normal to the axis A. In a typical system two lamp-gate-lens assemblies will be mounted in a single unit 10 (FIG. 4), the two assemblies having different light gates 7a and 7b such as are shown in FIGS. 2 and 3. Two units are normally used on each vehicle with the light gate 7a outermost in each case.

In FIG. 2 the first gage 7a comprises a circular opaque portion 11a with an aperture 8a in front of which is mounted a glass plate having a diffusely translucent frosted portion 12a and a clear or substantially greater light-transmitting portion 7 13a. The portion 12a can be frosted with a sandblast using No.

I grit. The translucent portion 12a is generally rectangular and elongate with respect to a horizontal plane HP through the optical axis A. Looking rearwardly toward the gate, on the right of a vertical plane VP through the axis A the translucent portion 12a is lower than on the left of the vertical plane. Because light rays from the lamp 3 are caused to cross from the bottom of the ellipsoidal reflector 6 through the gate to the top of the lens 9, as shown in FIG. I, and similarly cross from the right of the reflector, looking rearwardly, to the right of the lens looking forwardly, the greater light transmission of the above-described lower right translucent portion results in greater light transmission to the right, looking ahead. Similarly the clear portion 13a of the gate is disposed substantially en- I tirely to the right of the vertical plane VP, looking rearwardly,

the horizontal plane HP. The clear portion 13b transmits light substantially higher above the horizontal plane HP and axis A than does the first-described gate 7a.

The light distribution from the headlamp assembly is shown to the right of FIG. 4. The lamps of the assembly can be operated in three modes producing three light beam patterns, namely a LOW pattern, a brighter EXPRESSWAY pattern and a HIGH pattern. As shown in FIG. 4the LOW. pattern is produced by closing a switch S1 supplying electrical current from a battery B through a voltage-dropping resistor R to the filament 4a of the lamp 3 behind the first gage 70. Closing both switches S1 and S2 bypasses the resistor R applying full voltage to the filament 4a and producing the brighter EX- PRESSWAY pattern. The'same two beam patterns can be produced by the Cswitching circuit of FIG. 6 using a'lamp 3a with a low-intensity filament 4c and a high-intensity filament 4d behind the first gate 7a, in which case switches S1 and S2 are closed alternatively. In the third mode of operation a third HIGH beam pattern is produced by simultaneous closing of switches S1 and S3 in either'of the systems of FIGS. 4 and 6. The resultantHIGH beam is a composite of beams from filaments 4a and 4b through gates 7a and 7b respectively.

The three beam patterns of FIG. 4 and two comparative PRIOR LOW and PRIOR HIGH sealed beam headlamp patterns of FIG. 5 each include two-iso-candlepower contours which are representative of the light distribution as seen by a driver. Contours 21 and 24 of the present LOW pattern represent the outer limits respectively of 2,000 and 15,000 candlepower light intensity 60 feet in front of lamp 4a. Contours 22 and 25 of the present EXPRESSWAY pattern and contours 27 and 28 of the PRIOR LOW pattern also are respectively 2,000 and l5,000 candlepower limits. Contours 23 and 26 of the present HIGH pattern and contours 29 and 30 of the PRIOR HIGH pattern are respectively 2,000 and 20,000 candlepower limits. By way of example, three of the test points of the 1969 Federally adopted SAE Standard SAE J579a are shown as an encircled X. These test prints 31, 32 and 33 are located respectively down and 1 to the right of the axis A, and 15 above and 1 and 2 to the right of axis A. Intensity at these test points is not to exceed 2,000 candlepower as specified by SAE 1579a. Excess intensity at test point 31 would unduly glare in the eyes of oncoming drivers. Excess intensity at test points 32 and 33 would unduly shine through the rear window or on the mirror of a vehicle ahead. All the patterns in FIGS. 4 and 6 meet SAE standards.

By comparison of the present LOW pattern with the PRIOR LOW pattern it can be seen that the present LOW pattern has the advantage of providing more candlepower nearer the horizontal plane HP, thus extending visibility on the road ahead and to the left and right outside the foveal region of vision. At the same time, by virtue of the opaque extension 15 of gate 7a the 2,000 candlepower contour 21 of the present LOW bean dips further from test point 31, thereby reducing glare toward oncoming drivers. To the right of the vertical plane VP the 2,800 candlepower contour 21 is further from test points 32 and 33, thereby reducing glare toward preceding drivers. The present LOW beam pattern thus gives greater useful illumination in the foveal and extra-foveal visual regions with less interference with other drivers.

Further the LOW beam pattern may be expanded by switching to the EXPRESSWAY level increasing the useful illumination as above while retaining the reduced interference with other drivers.

Still further, the present LOW beam from gate 7a used in conjunction with the separate beam from gate 7b produces a high-beam pattern whose 2,000 candlepower contour 23 meets SAE standards but reduces glare in the upper left quadrant toward oncoming drivers compared to the PRIOR HIGH. The 20,000 candlepower contour 26 is also within acceptable limits but is wider and displaced substantially toward the lower right quadrant thereby increasing useful roadside illumination while reducing glare toward other oncoming and preceding drivers, as compared with the PRIOR HIGH contour 30.

It should be understood that the present disclosure is for the purpose of illustration only and that this invention includes all modifications and equivalents which fall within the scope of the appended claims.

I claim:

1. A vehicle headlight system comprising a second lamp closely adjacent the first,

optical means for projecting light from respective lamps on substantially parallel optical axes, said optical means including a first mask in front of the first lamp having a horizontally elongate aperture with greater transmission to the right of the axis of the first lamp, and a second mask in front of the second lamp having a generally vertically symmetrical aperture transmitting substantially,

higher above its optical axis than the first aperture, and

said lamps being adapted to be switched so as to operate in at least two different modes including operation of the first lamp alone and operation of the first and second lamps simultaneously,

thereby to produce a low light distribution pattern substantially below a horizontal plane through said axes, or a second light distribution pattern which is a composite of light from both lamps.

2. A system according to claim 1 characterized by switch means connected to supply power to the first lamp alone and to the first and second lamps together.

3. A system according to claim 1 characterized by switch means connected to supply high or low power to the first lamp alternatively, or simultaneously to supply low and normal power to the first and second lamps respectively.

4. A vehicle headlight system comprising a headlight housing,

first and second filamented lamps closely adjacent each other in the housing,

first and second optical means for projecting light from respective lamps on substantially parallel axes each defined by horizontal and vertical planes through the optical means, each optical means including an ellipsoidal reflector behind a lamp and having one focus at the lamp, and a mask in front of the lamp having an aperture at the second focus of the reflector,

the mask of the first optical means having a horizontally elongate, translucent portion vertically narrower on one side of said vertical plane than on the other and narrowest at said one side, and having a generally rectangular transparent portion inside the translucent portion primarily to said other side of the vertical plane,

the mask of the second optical system having a generally vertically symmetrical transparent portion primarily disposed above the aforesaid horizontal axis, and a translucent portion below the horizontal plane,

the lamp of the first optical means having filament means switchable between high and low intensities, and

means for switching the lamps in three modes: a first mode with the first lamp only burning at low intensity to produce a wide projected light beam pattern below the horizontal plane with a dip in intensity at a point just to the left of the horizontal plane and with increased intensity further to the left of the horizontal plane; a second mode with the first lamp burning at high intensity to produce a horizontally wider proljected light beam pattern of substantially the same vertica distribution; and a third mode with the first lamp burning at low-intensity and the second lamp also burning to produce a composite beam with highest intensity primarily below the horizontal plane and to the right of the vertical plane and lowest intensity above the horizontal plane and to the left of the vertical plane,

thereby to minimize glare toward oncoming drivers and increase illumination in the foveal region of the driver of the vehicle. 

1. A vehicle headlight system comprising a first lamp, a second lamp closely adjacent the first, optical means for projecting light from respective lamps on substantially parallel optical axes, said optical means including a first mask in front of the first lamp having a horizontally elongate aperture with greater transmission to the right of the axis of the first lamp, and a second mask in front of the second lamp having a generally vertically symmetrical aperture transmitting substantially higher above its optical axis than the first aperture, and said lamps being adapted To be switched so as to operate in at least two different modes including operation of the first lamp alone and operation of the first and second lamps simultaneously, thereby to produce a low light distribution pattern substantially below a horizontal plane through said axes, or a second light distribution pattern which is a composite of light from both lamps.
 2. A system according to claim 1 characterized by switch means connected to supply power to the first lamp alone and to the first and second lamps together.
 3. A system according to claim 1 characterized by switch means connected to supply high or low power to the first lamp alternatively, or simultaneously to supply low and normal power to the first and second lamps respectively.
 4. A vehicle headlight system comprising a headlight housing, first and second filamented lamps closely adjacent each other in the housing, first and second optical means for projecting light from respective lamps on substantially parallel axes each defined by horizontal and vertical planes through the optical means, each optical means including an ellipsoidal reflector behind a lamp and having one focus at the lamp, and a mask in front of the lamp having an aperture at the second focus of the reflector, the mask of the first optical means having a horizontally elongate, translucent portion vertically narrower on one side of said vertical plane than on the other and narrowest at said one side, and having a generally rectangular transparent portion inside the translucent portion primarily to said other side of the vertical plane, the mask of the second optical system having a generally vertically symmetrical transparent portion primarily disposed above the aforesaid horizontal axis, and a translucent portion below the horizontal plane, the lamp of the first optical means having filament means switchable between high and low intensities, and means for switching the lamps in three modes: a first mode with the first lamp only burning at low intensity to produce a wide projected light beam pattern below the horizontal plane with a dip in intensity at a point just to the left of the horizontal plane and with increased intensity further to the left of the horizontal plane; a second mode with the first lamp burning at high intensity to produce a horizontally wider projected light beam pattern of substantially the same vertical distribution; and a third mode with the first lamp burning at low-intensity and the second lamp also burning to produce a composite beam with highest intensity primarily below the horizontal plane and to the right of the vertical plane and lowest intensity above the horizontal plane and to the left of the vertical plane, thereby to minimize glare toward oncoming drivers and increase illumination in the foveal region of the driver of the vehicle. 